1. Field of the Invention
The invention relates to the field of medical devices. More particularly, the invention relates to a bone fixation apparatus.
2. Description of the Related Art
Injuries to the spine can occur from fractures of vertebra, bulging or slipped disks, infections, tumors, and other sources. Patients with such injuries can experience considerable pain. Some types of spinal injuries may be corrected through spinal surgery. In one type of spinal surgery, two or more adjacent vertebrae are fused together.
In order to fuse two vertebrae together, an incision is made over the location to be fused. Bone and tissue are removed from the joint to allow the vertebrae to fuse together into one unitary segment. A bone graft may sometimes be inserted into the disk space. Metal rods may be used to stabilize the spine while the vertebrae fuse together.
The structures that are inserted into the vertebra are often threaded screws, and because of their position in the vertebra, are often referred to as pedicle screws. The pedicle screws are placed along two or more adjacent vertebra and are attached to a rod that is used to support and stabilize the spine.
Pedicle screws and the associated rod support structures are secured together with a coupler that includes a threaded fastener inserted into or onto the coupler during the course of the surgery. However, because the fastener is threaded into the support structure during the course of surgery, it can be difficult to mate the threads accurately in a tight surgical field and there is the possibility of cross threading the screw.
What is desired is a support structure for use with a bone fixation apparatus that allows a support rod to be fixed with the force of a threaded fastener, and that is easier to install.